2,752 research outputs found
Energy Approach for Liquefaction of Sandy and Clayey Silts
The liquefaction potential of sandy and clayey silts is assessed in this paper using an energy approach original developed for sand. Three series of laboratory tests were conducted to examine the liquefaction resistance of clean silt, sandy silt and clayey silt. The test results have been analyzed to establish a liquefaction failure criterion for silty soils. Based on this criterion, the case records of a new database have been studied and the results suggest that a single criterion can be used for sand, silt, sandy silt and clayey silt. For sandy or silty soils without clay content, the criterion is expressed in terms of the earthquake magnitude, hypocentral distance and the corrected standard penetration resistance. For clayey silt, the same criterion and parameters can be used except the standard penetration resistance has to be modified in terms of the clay content
The links between magnetic fields and filamentary clouds III: field regulated mass cumulative functions
During the past decade the dynamical importance of magnetic fields in
molecular clouds has been increasingly recognized, as observational evidence
has accumulated. However, how a magnetic field affect star formation is still
unclear. Typical star formation models still treat a magnetic fields as an
isotropic pressure, ignoring the fundamental property of dynamically important
magnetic fields: their direction. This study builds on our previous work which
demonstrated how the mean magnetic field orientation relative to the global
cloud elongation can affect cloud fragmentation. After the linear mass
distribution reported earlier, we show here that the mass cumulative function
(MCF) of a cloud is also regulated by the field orientation. A cloud elongated
closer to the field direction tends to have a shallower MCF, in other words, a
higher portion of the gas in high density. The evidence is consistent with our
understanding of bimodal star formation efficiency discovered earlier, which is
also correlated with the field orientations.Comment: Accepted by MNRAS on 11 August 202
Lessons learned from inadequate implementation planning of team-based chronic disease management: implementation evaluation.
BACKGROUND: This study was a retrospective evaluation of an unsuccessfully implemented team-based, chronic disease management program, with an aim to understand more about implementation barriers. The program, the Chronic Disease Management Initiative (CDMI) was a new collaborative model of care for patients with COPD. It utilized customized health information and interactive tools, mainly smartphones, for ongoing disease management. The program\u27s goal was to demonstrate that integrated team-based models of care could improve patient care, as well as reduce readmission rates and emergency department visits. The program planning for CDMI began in 2017, followed by the implementation and evaluation period in 2018. After a 10-month implementation period, the program was unable to enroll a sufficient number of patients to examine if there was an improvement in patient outcomes.
METHODS: A retrospective case-study design using multiple data sources was used to gather feedback from participants involved in CDMI. Data collection occurred throughout planning and implementation and continued into early 2019. Semi-structured interviews were conducted, and transcripts were analyzed using NVivo 10 software. This was followed by content analysis.
RESULTS: Analysis revealed four key themes as barriers to CDMI\u27s implementation: 1) lack of a needs assessment with key stakeholders; 2) lack of buy-in from medical staff; 3) inadequate patient engagement and; 4) contextual barriers. Planners did not conduct a proper needs assessment, nor include patients in the study design. In addition, there was insufficient consideration for how CDMI should be integrated into the usual COPD care plan, leading to confusion in roles and responsibilities. Poor communication between the implementation team and healthcare providers implementing the program, led to a lack of buy-in and engagement.
CONCLUSION: The key themes resonate with what is already known in the literature. This study supports the importance of using a theoretically grounded plan for implementation. Using a model only in the planning stages is insufficient even when an intervention is based on evidence to support higher quality care. It is imperative to consider practical and contextual factors of program implementation and their interactions. By detailing the \u27failed implementation\u27 of this intervention, we hope to share important lessons about the need to plan implementation processes early in program planning
Mitochondria-targeted spin-labelled luminescent iridium anticancer complexes
Mitochondria generate energy but malfunction in many cancer cells, hence targeting mitochondrial metabolism is a promising approach for cancer therapy. Here we have designed cyclometallated iridium(III) complexes, containing one TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) spin label [C43H43N6O2Ir1·PF6]˙ (Ir-TEMPO1) and two TEMPO spin labels [C52H58N8O4Ir1·PF6]˙ (Ir-TEMPO2). Electron paramagnetic resonance (EPR) spectroscopy revealed spin–spin interactions between the TEMPO units in Ir-TEMPO2. Both Ir-TEMPO1 and Ir-TEMPO2 showed bright luminescence with long lifetimes (ca. 35–160 ns); while Ir-TEMPO1 displayed monoexponential decay kinetics, the biexponential decays measured for Ir-TEMPO2 indicated the presence of more than one energetically-accessible conformation. This observation was further supported by density functional theory (DFT) calculations. The antiproliferative activity of Ir-TEMPO2 towards a range of cancer cells was much greater than that of Ir-TEMPO1, and also the antioxidant activity of Ir-TEMPO2 is much higher against A2780 ovarian cancer cells when compared with Ir-TEMPO1. Most notably Ir-TEMPO2 was particularly potent towards PC3 human prostate cancer cells (IC50 = 0.53 μM), being ca. 8× more active than the clinical drug cisplatin, and ca. 15× more selective towards cancer cells versus normal cells. Confocal microscopy showed that both Ir-TEMPO1 and Ir-TEMPO2 localise in the mitochondria of cancer cells
iPTF16geu: A multiply imaged, gravitationally lensed type Ia supernova
We report the discovery of a multiply-imaged gravitationally lensed Type Ia
supernova, iPTF16geu (SN 2016geu), at redshift . This phenomenon could
be identified because the light from the stellar explosion was magnified more
than fifty times by the curvature of space around matter in an intervening
galaxy. We used high spatial resolution observations to resolve four images of
the lensed supernova, approximately 0.3" from the center of the foreground
galaxy. The observations probe a physical scale of 1 kiloparsec, smaller
than what is typical in other studies of extragalactic gravitational lensing.
The large magnification and symmetric image configuration implies close
alignment between the line-of-sight to the supernova and the lens. The relative
magnifications of the four images provide evidence for sub-structures in the
lensing galaxy.Comment: Matches published versio
Classical Novae in Andromeda: Light Curves from the Palomar Transient Factory and GALEX
We present optical light curves of twenty-nine novae in M31 during the 2009
and 2010 observing seasons of the Palomar Transient Factory (PTF). The dynamic
and rapid cadences in PTF monitoring of M31, from one day to even ten minutes,
provide excellent temporal coverage of nova light curves, enabling us to record
the photometric evolution of M31 novae in unprecedented detail. We also detect
eight of these novae in the near ultraviolet (UV) band with the Galaxy
Evolution Explorer (GALEX) satellite. Novae M31N2009-10b and 2010-11a show
prominent UV emission peaking a few days prior to their optical maxima,
possibly implying aspherical outbursts. Additionally, our blue-shifted spectrum
of the recent outburst of PT And (M31N2010-12a) indicates that it is a
recurrent nova in M31 and not a dwarf nova in the Milky Way as was previously
assumed. Finally, we systematically searched for novae in all confirmed
globular clusters of M31 and found only M31N 2010-10f associated with Bol 126.
The specific nova rate in the M31 globular cluster system is thus about one per
year which is not enhanced relative to the rate outside the globular cluster
system.Comment: 18 pages, 13 figures, submitted to Ap
A subgroup of SGS3-like proteins act redundantly in RNA-directed DNA methylation
Plant specific SGS3-like proteins are composed of various combinations of an RNA-binding XS domain, a zinc-finger zf-XS domain, a coil–coil domain and a domain of unknown function called XH. In addition to being involved in de novo 2 (IDN2) and SGS3, the Arabidopsis genome encodes 12 uncharacterized SGS3-like proteins. Here, we show that a group of SGS3-like proteins act redundantly in RNA-directed DNA methylation (RdDM) pathway in Arabidopsis. Transcriptome co-expression analyses reveal significantly correlated expression of two SGS3-like proteins, factor of DNA methylation 1 (FDM1) and FDM2 with known genes required for RdDM. The fdm1 and fdm2 double mutations but not the fdm1 or fdm2 single mutations significantly impair DNA methylation at RdDM loci, release transcriptional gene silencing and dramatically reduce the abundance of siRNAs originated from high copy number repeats or transposons. Like IDN2 and SGS3, FDM1 binds dsRNAs with 5′ overhangs. Double mutant analyses also reveal that IDN2 and three uncharacterized SGS3-like proteins FDM3, FDM4 and FDM5 have overlapping function with FDM1 in RdDM. Five FDM proteins and IDN2 define a group of SGS3-like proteins that possess all four-signature motifs in Arabidopsis. Thus, our results demonstrate that this group of SGS3-like proteins is an important component of RdDM. This study further enhances our understanding of the SGS3 gene family and the RdDM pathway
Dramatic reduction of surface recombination by in-situ surface passivation of silicon nanowires
Nanowires have unique optical properties [1-4] and are considered as
important building blocks for energy harvesting applications such as solar
cells. [2, 5-8] However, due to their large surface-to-volume ratios, the
recombination of charge carriers through surface states reduces the carrier
diffusion lengths in nanowires a few orders of magnitude,[9] often resulting in
the low efficiency (a few percent or less) of nanowire-based solar cells. [7,
8, 10, 11] Reducing the recombination by surface passivation is crucial for the
realization of high performance nanosized optoelectronic devices, but remains
largely unexplored. [7, 12-14] Here we show that a thin layer of amorphous
silicon (a-Si) coated on a single-crystalline silicon nanowire (sc-SiNW),
forming a core-shell structure in-situ in the vapor-liquid-solid (VLS) process,
reduces the surface recombination nearly two orders of magnitude. Under
illumination of modulated light, we measure a greater than 90-fold improvement
in the photosensitivity of individual core-shell nanowires, compared to regular
nanowires without shell. Simulations of the optical absorption of the nanowires
indicate that the strong absorption of the a-Si shell contributes to this
effect, but we conclude that the effect is mainly due to the enhanced carrier
lifetime by surface passivation
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